Zygote
Zygote | |
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pronuclei are converging, but the genetic material is not yet united. | |
Details | |
Days | 0 |
Precursor | Gametes |
Gives rise to | Blastomeres |
Identifiers | |
MeSH | D015053 |
TE | E2.0.1.2.0.0.9 |
FMA | 72395 |
Anatomical terminology] |
Part of a series on |
Human growth and development |
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Stages |
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A zygote (, the result of which is the formation of a diploid cell called the zygote or zygospore.
History
German zoologists Oscar and Richard Hertwig made some of the first discoveries on animal zygote formation in the late 19th century.
In multicellular organisms
The zygote is the earliest developmental stage. In humans and most other anisogamous organisms, a zygote is formed when an egg cell and sperm cell come together to create a new unique organism.
The formation of a totipotent zygote with the potential to produce a whole organism depends on epigenetic reprogramming. DNA demethylation of the paternal genome in the zygote appears to be an important part of epigenetic reprogramming.[2] In the paternal genome of the mouse, demethylation of DNA, particularly at sites of methylated cytosines, is likely a key process in establishing totipotency. Demethylation involves the processes of base excision repair and possibly other DNA-repair–based mechanisms.[2]
Humans
In
After fertilization, the conceptus travels down the
The human zygote has been genetically edited in experiments designed to cure inherited diseases.[10]
Fungi
In fungi, this cell may then enter meiosis or mitosis depending on the life cycle of the species.[citation needed]
Plants
In plants, the zygote may be polyploid if fertilization occurs between meiotically unreduced gametes.
In land plants, the zygote is formed within a chamber called the archegonium. In seedless plants, the archegonium is usually flask-shaped, with a long hollow neck through which the sperm cell enters. As the zygote divides and grows, it does so inside the archegonium.[citation needed]
In single-celled organisms
The zygote can divide asexually by mitosis to produce identical offspring.[citation needed]
A Chlamydomonas zygote contains chloroplast DNA (cpDNA) from both parents; such cells are generally rare, since normally cpDNA is inherited uniparentally from the mt+ mating type parent. These rare biparental zygotes allowed mapping of chloroplast genes by recombination.[citation needed]
See also
- Breastfeeding and fertility
- Fertilization
- Proembryo
References
- ^ "English etymology of zygote". etymonline.com. Archived from the original on 2017-03-30.
- ^ PMID 27916276.
- ^ Blastomere Encyclopædia Britannica Archived 2013-09-28 at the Wayback Machine. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Web. 06 Feb. 2012.
- PMID 24368070.
- ^ "Report of the Human Embryo Research Panel" (PDF). Archived from the original (PDF) on 2009-01-30. Retrieved 2009-02-17.
- ^ O’Reilly, Deirdre. "Fetal development Archived 2011-10-27 at the Wayback Machine". MedlinePlus Medical Encyclopedia (2007-10-19). Retrieved 2009-02-15.
- ^ Klossner, N. Jayne and Hatfield, Nancy. Introductory Maternity & Pediatric Nursing, p. 107 (Lippincott Williams & Wilkins, 2006).
- ^ Neas, John F. "Human Development" Archived July 22, 2011, at the Wayback Machine. Embryology Atlas
- ^ Blackburn, Susan. Maternal, Fetal, & Neonatal Physiology, p. 80 (Elsevier Health Sciences 2007).
- ^ "Editing human germline cells sparks ethics debate". May 6, 2015. Archived from the original on May 18, 2015. Retrieved May 17, 2020.